SIRIAS: a simulation model for sprinkler irrigation - II. Calibration and validation of the model

The SIRIAS model has been developed to simulate water distribution of a spr inkler pattern distorted by wind, thereby eliminating the necessity of carr ying out laborious in-field tests to determine water distribution in a irri gation system. The model is based on the application of a ballistic theory to drop movement distorted by wind. The necessary data correspond basically to the radial distribution test of the sprinkler. The model has been calib rated and validated using field tests for the different combinations of spr inkler-nozzle-height. The following internal performance parameters of the simulation model SIRIAS are considered as optimal: number of throw directio ns (180), drop diameter increment (0.05 mm)l number of iterations per secon d (50). The corrector coefficients that best fit the simulated and in-field measured water distribution pattern at 350 kPa for block irrigation tests were: K-1 = 1.85 and K-2 = 0.15. The mean absolute error in block irrigatio n CU values was 2.7%.